What are the uses of pituitary hormones in clinical practice?

Pituitary Hormones and Their Clinical Uses

Pituitary hormones are essential for numerous physiological functions and are used therapeutically to treat various endocrine disorders, with growth hormone (GH) being the most widely used for conditions like growth failure in chronic kidney disease and adult GH deficiency.

Major Pituitary Hormones and Their Clinical Applications

Growth Hormone (GH)

• Primary clinical uses:

  • Treatment of growth failure in children with chronic kidney disease (CKD) stages 3-5 1
  • Growth hormone deficiency in children and adults 2, 3
  • Short stature in Turner syndrome 1, 4
  • Idiopathic short stature 4
  • Growth failure in children with nephropathic cystinosis 1

• Dosing and administration:

  • Pediatric CKD patients: 0.045-0.05 mg/kg/day subcutaneously 1
  • Adult GH deficiency: 0.0125-0.025 mg/kg/day 4
  • Evening administration recommended to mimic physiological secretion 1
  • Daily subcutaneous injections with rotation of injection sites to prevent lipoatrophy 1

• Monitoring requirements:

  • Regular height velocity measurements
  • IGF-1 levels
  • Fundoscopic examination before initiation to rule out papilledema 1
  • Glucose tolerance monitoring 4
  • Bone age assessment via wrist radiography 1

ACTH (Adrenocorticotropic Hormone) and Cortisol Replacement

• Clinical uses:

  • Diagnosis and management of adrenal insufficiency 1, 5
  • Replacement therapy in hypopituitarism 6

• Management approach:

  • Primary adrenal insufficiency: Both glucocorticoid and mineralocorticoid replacement 5
  • Secondary adrenal insufficiency: Glucocorticoid replacement only 5
  • Hydrocortisone is the preferred glucocorticoid (10-20 mg morning, 5-10 mg afternoon) 1
  • Stress dosing required during illness or procedures 5

• Monitoring:

  • Clinical symptoms, weight, blood pressure
  • Morning cortisol levels
  • Electrolytes (especially in primary adrenal insufficiency) 5
  • Note: GH therapy can reduce circulating cortisol levels during hydrocortisone replacement 7

Thyroid Stimulating Hormone (TSH) and Thyroid Replacement

• Clinical uses:

  • Central hypothyroidism in hypopituitarism 1
  • TSH-secreting adenomas (rare) 8

• Management approach:

  • Levothyroxine replacement based on weight 1
  • In hypopituitarism with multiple deficiencies, always start corticosteroids before thyroid replacement 1
  • Follow free T4 for dose titration (TSH is not accurate in central hypothyroidism) 1

Gonadotropins (LH/FSH) and Sex Hormone Replacement

• Clinical uses:

  • Hypogonadotropic hypogonadism 1
  • Fertility treatment 8

• Management approach:

  • Males: Testosterone replacement therapy 1
  • Females: Estrogen/progesterone replacement 1
  • Consider in patients with fatigue, loss of libido, and mood changes 1

Special Considerations in Pituitary Hormone Therapy

Growth Hormone in CKD Patients

• Indications:

  • Height below the third percentile for age and sex AND
  • Height velocity below the twenty-fifth percentile 1
  • Consider in children with height between third and tenth percentile with persistent low velocity 1

• Contraindications:

  • Closed epiphyses 1
  • Known hypersensitivity to GH 1
  • Severe secondary hyperparathyroidism (PTH >500 pg/ml) 1
  • Active malignancy 1

• Potential adverse effects:

  • Intracranial hypertension (rare) 4
  • Glucose intolerance 4
  • Slipped capital femoral epiphysis 4
  • Progression of scoliosis 4
  • Edema 4

Pituitary Hormone Replacement After Pituitary Surgery or Radiation

• Sequence of hormone loss:

  • Typically GH first, followed by gonadotropins, TSH, and ACTH 8

• Replacement priorities:

  • Cortisol first, then thyroid hormones, then sex hormones, and finally GH if needed 8
  • In Cushing's disease patients in remission, consider GH testing and early replacement to promote catch-up growth 1

Adrenal Crisis Management

• Emergency treatment:
  • Hydrocortisone 100 mg IV immediately 5
  • Followed by 100-300 mg/day as continuous infusion or divided doses 5
  • Rapid IV isotonic saline administration 5
  • All patients need education on stress dosing and medical alert bracelet 1

Pitfalls and Caveats

1. Timing of multiple hormone replacements:

   • Always start corticosteroids several days before thyroid hormone to prevent precipitating adrenal crisis 1

2. Monitoring challenges:

   • In central hypothyroidism, TSH levels are unreliable; monitor free T4 instead 1
   • GH therapy can alter cortisol metabolism, potentially requiring adjustment of glucocorticoid dosing 7

3. Growth hormone therapy considerations:

   • Before starting GH, address other treatable causes of growth failure (malnutrition, metabolic acidosis, CKD-MBD) 1
   • Fundoscopic examination before initiation to rule out pre-existing papilledema 1
   • Regular monitoring for potential adverse effects, especially in high-risk groups 4

4. Special populations:

   • Turner syndrome: Increased risk of otitis media and cardiovascular disorders with GH therapy 4
   • Post-transplant: Consider GH therapy 1 year after transplantation if spontaneous catch-up growth doesn't occur 1
   • Cushing's disease in remission: Early GH replacement recommended if deficient 1

By understanding the appropriate uses, dosing, monitoring requirements, and potential complications of pituitary hormone therapy, clinicians can optimize outcomes while minimizing risks in patients with pituitary disorders.